1. Field of the invention
The present invention relates to a color adjustment apparatus for a color picture image reproducing machine.
2. Discussion of the background
In general, conventional analog color copying machines require color adjustment since there are many cases where the color tone of a copy image which has been produced from an original document differs from the original color tone. Such color adjustment is very important, but it involves difficulties in technical terms.
In a conventional type of color adjustment system, the color tone of a copy image is adjusted or corrected by separating the original color into the three elements of color, that is, brilliance, saturation and hue and inputting the amount of color adjustment for each of the elements by a predetermined key operation. Specifically, exposure outputs, main-charge outputs, development bias outputs and the like are adjusted by operating a variable resistor or the like in order to effect color adjustment. As a result, it is difficult for a user to transmit to the copying machine his desire to make the color of a copy slightly dim or somewhat closer to orange. For this reason, it is difficult for the user to perform the desired color adjustment.
The input system for the amount of color adjustment in such a conventional color adjustment system is typically arranged such that the amount of color adjustment is input by incrementing or decrementing a numerical value through the operation of keys provided with symbols or numbers such as "+", "-", "1", "2", "3", "4" and "5". However, such a system has the following problems. Since such symbols or numbers have no visual appeal, the user cannot understand how the color changes as a result of the increment or decrement based on a single key operation. It is therefore difficult for the user to accomplish the desired color correction through a single operation. In other words, the user cannot understand whether the color has been adjusted by the desired amount until a trial copy is actually produced. For this reason, the user requires a certain learning period until he grasps the performance of the copying machine.
In such a conventional color adjustment system, a plurality of keys for each of brilliance, saturation and hue must be laid out on an operating panel. As a result, the user may have an impression that the operation of the machine is difficult. In addition, in the current situation in which color copying machines are used in various countries, the function of each key must be represented in a variety of languages. This leads to an increase in the number of production steps, and there is a risk that a discrepancy may occur between the image associated with a functional representation and the actual result of corresponding control.
Briefly, such a conventional type of color adjustment system has the problem that a difficult operation is required and that, if the operability is improved, a desired color copy cannot be obtained.
Such a full-color copying machine typically employs three kinds of color toner, that is, yellow Y toner, magenta M toner and cyan C toner, and is capable of producing a full-color copy by a combination of these three kinds as well as a single-color copy (monocolor copy). Therefore, it is possible to provide single-color copies of the six colors yellow Y, magenta M, cyan C, blue B (a combination of magenta M and cyan C), green G (a combination of yellow Y and a cyan C) and red R (a combination of yellow Y and magenta M). Some types of copying machines are arranged so that single-color copies of twelve colors such as Y, M, C YM, YC, MC, YYM, YMM, MMC, MCC YYC and YCC can be provided by a combination of the toner of the three kinds of Y, M and C.
As described above, when a single-color copy is to be produced with such a conventional type of color copying machine, it is impossible to select a desired single color from among many kinds of colors since each color is only reproduced by either one selected from the three kinds of toner Y, M and C or a combination of two of the three.
Many of the conventional color copying machines are arranged such that a color selecting operation in the above-described single-color copying operation is performed by specifying a character key such as a "RED" key or a "YELLOW" key on an operating panel. Therefore, there are many cases where the color of a copy image which has been produced from an original is not the same as the color which the user imaged. In addition, in order to enable twelve kinds of single-color copies, it has been necessary to lay out twelve single-color selection keys on the operating panel. Accordingly, since an increased number of keys must be arranged, users may have the impression that the operation of the operating panel is difficult and complicated.